Fundamental to sustaining port operations

Among the impacts of climate change on ports, more frequent episodes of coastal erosion, flooding within ports and in coastal areas and also greater runoff and sedimentation are anticipated, which will mean more dredging operations.

Any dredging operation requires complete environmental impact studies to analyse the origin and destination of the dredged materials, and the effects of this activity on the biotic environment, on the landscape, on economic activities, on infrastructures and on possible protected areas, among others.

One of the reasons for this is that this type of operation can alter the physical and chemical parameters of the environment, such as turbidity¹, and release pollutants from the sediment, incorporating them into the water column where the dredged material is dumped. It is however important to note that dredging is a very necessary activity within ports, allowing them to operate by adjusting channel depths for deep-draught vessel traffic.

The existence of impacts linked to dredging doesn't mean that preventive and corrective measures can't be established to mitigate them, ensuring these operations are compatible with appropriate and necessary environmental control. Some of these measures can include selecting favourable dates and environmental conditions for disposal (swell, tides, currents, wind conditions, etc.), choosing the dredging system to prevent sediment resuspension, and fundamentally, carrying out comprehensive monitoring of the processes through an Environmental Monitoring Plan. This allows for intervention and correction as soon as anomalies are detected.

Suggestions/Ideas

• Prioritise the reuse of dredged materials rather than dumping them if legislation permits.
• Monitor before, during and after dredging operations for environmental impact.
• Plan dredging operations in advance in order to benefit from the most favourable conditions; not waiting until dredging is urgently required.
• In general, when considering management options for dredged material, the preferred option should be to retain the dredged material within the same aquatic sediment system from which it originated (beach regeneration or harbour fill), provided that it is technically, socially, economically and environmentally feasible to do so.
• Consult the standards and recommendations defined in each region for the characterisation of dredged material, including the provisional definition of pollution thresholds to assess the environmental acceptability of dumping at sea (action levels), the necessary studies for the selection of the dumping area and corresponding environmental monitoring programmes.

Resources:

• The UN Environment Programme (UNEP) maintains updated guidelines on the management of dredging operations and dredged materials.

1 Turbidity is a phenomenon that decreases the transmission of light in the water column, which given sufficient intensity and duration is sufficient, can affect ecosystems present in the area. Turbidity produced as a result of dredging occurs due to suspended particles remaining in the water column, creating two measurable factors: the amount of material held in suspension, and the period of time that the material remains in the water column during the dredging process.